With the rapid development of communication technology, information exchange among people appears more and more frequently. A single mobile communication terminal, such as a mobile phone or a vehicle-mounted mobile terminal may not meet the needs of people, especially those engaged in marketing or management, who may have to carry two or more mobile terminals to meet the communication requirements, which brings inconvenience. Nowadays, multi-SIM communication terminals are emerging, which makes a user only need to carry one communication device with more than one card, such as Subscriber Identity Module (SIM) cards or Universal Subscriber Identity Module (USIM) cards. It is far more convenient than the conventional way to carry several mobile terminals.
In general, if a subscriber wants to use multiple phone numbers in a single mobile terminal, the following solutions may be employed.
Firstly, a multi-SIM single-standby communication terminal may be used. In this communication terminal, there is more than one card simultaneously, however, only one card can be used (be set in a standby state) at the same time, and switching among the multiple cards is executed by hardware circuits, which is generally selected when the device is powered on. Due to the effect of a protocol stack, the switching among the multiple cards can not be executed dynamically when the communication device is in operation. For this matter, the mobile phone system needs to be rebooted (mainly reboot protocol stack or upper-layer software) to switch among the multiple cards.
Secondly, a multi-SIM multi-standby communication device may be used to overcome the disadvantages in the multi-SIM single-standby communication device, in which multiple cards can be standby simultaneously and in-coming calls of the multiple cards can be received simultaneously, just like carrying multiple mobile terminals with a single card, thereby improving practical application greatly.
An early multi-SIM multi-standby communication terminal actually possesses multiple sets of systems, generally two, each of which has a radio frequency (RF) transceiver module, a baseband processing module, and a protocol stack respectively. The communication device having multiple systems can realize multiple SIM cards respectively in standby or communicating state, which is also referred to as a multi-SIM multi-standby multi-communicating communication device. However, this kind of communication terminal, with multiple systems utilized, suffers an additional cost and power consumption, and a larger size, which causes inconvenience. In view of radio frequency modules, allowing for co-channel interferences, one radio frequency (RF) module is generally configured at the top of a mobile phone, and the other one is configured at the end of the mobile terminal, so as to reduce interferences. Generally, the distance between the two antennae is greater than 100 mm.
Later multi-SIM multi-standby mobile terminal is a kind of multi-SIM multi-standby single-communicating communication device, which uses only one set of communication module, compared to the early multiple systems. Because the upper protocol stacks needs to cooperate, the protocol stacks which operate independently in the early multi-SIM multi-standby multi-communicating communication device needs a close integration. Although the practical operation becomes more complicated, the multi-SIM multi-standby function may be achieved.
As for the conventional multi-SIM multi-standby mobile terminal, upon being powered on, the multiple cards search for a network and camp on a cell independently. Therefore, multiple cards may camp on multiple different cells at the same time.
Even if multiple cards have the possibility to camp on an identical cell, neighbouring cells measurement and cell reselection are performed independently. That is, some of the multiple cards may reselect a new cell, while some of the multiple cards still camp on the original cell. As a result, the multiple cards may still camp on multiple different cells.
As for multi-SIM multi-standby single-communicating communication device, due to one set of communication module, paging information reception and neighbouring cells measurement can only be time-division switched in turn for each cell. In the event that multiple cards camp on multiple different cells, the efficiency of paging information reception is inverse proportional to the number of cards in standby states. The chance of neighbouring cells measurement is reduced with the increase of the number of cards in standby states.
With regard to power consumption, because each card camps on different cell independently, and paging information reception and neighbouring cells measurement need to be time-division switched in turn for each cell, the idle time is much shorter than that of the single-standby communication terminal, which thereby causes higher power consumption.